Method of vacuum sealing



June 4, 1946. c. HERZOG E TA.L

METHOD OF VACUUM SEALING 2 Sheets-Sheet l /IIIIIIIIL Filed July 19, 1943C'arlflerzo a nd PauZA.Hau-ck.

June 4, 1946. I c. HERZOG gm 2,401,638

' METHOD OF VACUUM SEALING Filed July 19' 1943 2 Sheets-Sheet 2 VA CUUMUN 144C (ll/M ON v I p.16: $2.113 tym f'j V4cuum VACUUM 0N 5/101- OFF -392 60: rZ Harte an a? Paul AhHau ck.

Patented June 4, 1946 z,4q1,63s'

UNlTED j srArEs PATENT orrica 0..., 11:13:11: fmi ffif, m...

by mesne assignments, to

N- themselves as joint tenants Application July 19, 1943, Serial110.0534? l The present invention relates to a method of vacuum sealingreceptacles.

An important object of the invention is to provide a method of the abovementioned character for vacuum sealing receptacles having metallicparts, metallic receptacles and glass receptacles. A further object ofthe invention is to provide a method of the above mentioned characterfor sealing radio vacuum tubes, thermionic tubes and lamps, such asfluorescent lamps, without the use of the usual exhaust tubes attachedto the same, whichmay be formed of metal or glass.

A further object of the invention is to provide a method of the abovementioned character which will eliminate the long exhaust tube used invacuum sealing, 95% of which is usually thrown away. after thesealingoperation is completed. A furtherobject ol the invention is toprovide a method of the above mentioned character which will eliminatethe use of the compression rubber 14 Claims. (Cl. 226-202) Figure 8 is acentral vertical longitudinal section through one end or afluorescent'lamp and associated vacuum connection,

Figure 8 is a Plan view of the fluorescent lamp,

Figure 9 is a central vertical section through the based the fluorescentlamp, parts broken away,.show ing the use of a cold forming tool and thefusing of the pellet to the base,

Figure 10 is a similar view showing the vacuum connection fused to theupper end of the pellet, with thevacuum cut oil, I

Figure 11 is a similar view showing the vacuum connection fused to thepellet and the vacuum connection and base cold and the vacuum turned onand the plunger raised,

Figure 12 is a similar view, showing the vacuum I connection heated andmoved downwardly to close the bore of the pellet, the plunger beingnipple of the usual vacuum machine, which nipple receives the exhausttube carried by the envelope.

Other objects and advantages of the'invention will be apparent duringthe course of the following description.

In the accompanying drawings forming a part or this application and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a central vertical longitudinal seca recess or depressionformed in the top of the metallic shell, before the base is applied tothe shell,

Figure 2 is a similar view, parts broken away, showing a tubular soldermaterial pellet placed within the recess,

Figure 3 is a similar view, parts broken away, showing a cold formingtool engaging the tubular solder material pellet,

Figure 4 is a similar view, parts broken away,

showing the base applied to the metallic shell and a tubular metallicexhaust connection engaging the tubular solder material pellet.

Figure 5 is a similar view, parts broken away. showing the tubularexhaust connection moved downwardly to. close the tubular pellet,

Figure 6 is a similar view, showing the tubular exhaust connectionraised andseparated from the tubular pellet, I y

Figure 7 is a central vertical section, parts bro ken away. through atin can equipped with a recessand tubular pellet for vacuum sealing thesame,

in the lowered position and the vacuum on and the base cold, Figure 13is a similar view, with the parts in the same position with the vacuumconnection the pellet filled with additional sealing wax. tion through aradio vacuum tube shell, showing In Figures 1 to 6 inclusive, thenumeral l0 designates a metal shell or envelope of a radio vacuum tubeor the like. This shell has an upper closed end or part II, providedpreferably centrally thereof with a cylindrical inwardly formed portionl2, producing a recess IS. The top of the cylindrical portion I2 is openwhile its bot-- .and this bore has a length considerably greater thanits diameter. Satisfactory results are ob-j tained byhaving thelen'gthof the bore substantially twice that of the diameter of such bore. Byemploying a tubular pellet having an elongated bore,the lower portion orbottom of the pellet may be chilled or rendered solid or main- .dure.

portion is ing a main bore 22 in communication with a source of vacuum.This bore 22 is in communication with a port 23, communicating with arecess 24 formed in the forward end of the tubular connection 2|. Therecess 24 isconcentric with the port 23 and is frustro-conical invertical cross section, providing a face or wall which tapers upwardly,as shown.

The cylindrical portion |2 forming the recess 13 'is preferably formedupon the metallic shell l while this shell is being produced, but theinvention is in no sense restricted to this proce- The shell l0 providedwith the recess I3 is now suitably supported in a vertical position withits top I uppermost, and the tubular solder material pellet I1 isinserted within the recess l3, and the shell l0 and pellet I! being coldor at room temperature. When the pellet I1 is inserted within the recessl3, its bottom. contacts with and is supported by the upper end of thetapered head M. The bore of the tubular pellet is larger perature. Whenthe lower end of the tubular pellet I! was heated, as explained, theheat treatment is regulated or stopped before the upper this heattreatment, the upper endof the pellet l1 and tool is may be chilled byblowing cold air upon thesame, and this will prevent. the upper endbeing sweated or fused to the tool I8.

The above described operations are performed upon the shell l0 previousto the assembly of the base and; elements carried'by the base with theshell. The base which may be formed of glass, is now applied to thelowerend of the shell l0, Figure 4, in'any well known manner and formsan air-tight Joint therewith. Thisbase carries the usual parts of aradio vacuum tube. I

The base 25' is applied to the shell in, as stated, and the shell I 0 isagain vertically supp rted with its top. uppermost, and the tubularexhaust connection2| is arranged above the tubular pellet l1 and moveddownwardly so that the tapered upper formed end of the pellet enters thetapered recess 24, these parts being correspondingly tathan the port l5and is slightly larger than the upper end of the tapered head l4, sothat the upper reduced end of the head l4 extends for a short distanceinto the bore of the tubular pellet.

The top of the tubular pellet projects above the top H, as shown.

The cold forming tool I8 is now positioned over the'tubular pellet l1and its pin I! inserted into "the bore of the tubular pellet, while thetop of the tubular pellet contacts with the upwardly ta- I the tubularpellet prevents the tubular pellet from collapsing and maintains itsbore open during this cold forming. The downward pressure. upon thetubular pellet, causes its bottom to slide down 7 the inclined face Itor the head I4, whereby the top end of the head |4 projects further intothe bore of the tubular pel1et.,'.Thisprevents the liability of anysmall particles of the solder material from the tubular pellet enteringthe shell "I. After the cold forming step, the downward pressure uponthe tool I8 is removed, and only.

pered so that the end fits snugly within the recess. The tapered recess24 is tinned with solder and engages the upper tapered end of thetubular pellet and is held in firm engagement therewith. Heat is, nowapplied to the tubular suction or vacuum connection 2|, preferablyatabout the point B, Figure 4, and passes by conduction to the engagingfaces of the recess 24 and the tubular pellet, and this heat causes thetop of the pellet to be fused to the wall ofthe recess 24, forming asolid air tight connection between the tubular vacuum connection 2| andthe shell Hi. The tubular vacuum connection 2| and the tubular pellet llare now cooled to room or atmospheric temperature, which may be effectedby blowing air thereon. With the tubular vacuum connection 2| thusrigidly secured to the tubular pellet and forming an air tightconnection therewith, the

vacuum valve of the vacuum pump is now opened of vacuum, heatis againapplied to the tubular vacuum connection 2|, preferably at about thepoint B, Figure 4', and passes by conduction to the top 'of the tubularpellet Lcausing the upper portion of the pelletto plastlclze. While thisoccurs, the tubular vacuum connection 2| is moved downwardly, to followup the flow of the 'fplasticized solder at the top of the pellet, and

- and downwardly, thereby closing the upper end-of the bore II, byforming a bridge Figure 5.

' This inward moving or forming of the plasticized material toward thecenter of the bore I1 is effected by the frustro-conical ortaperedrecess 24,,

suitably heated, at about the point A, and this heat is transferred byconduction to the lower 'cnd of the tubular pellet, and this lower endis then sweated to the inclined face of the head M pellet and the shellI 0, which are sweated or fused together, are cooled to room oratmospheric temwhen .the connection 2| is moved downwardly. At the sametime that the tubular vacuum connection 2| is being heated, the top ofthe shell l0 is chilled or cooled to prevent the lower portion or bottomof the pellet from plasticizing. This cooling-may be effected by blowingcold air upon :the shell II) at about the point A, Figure 5. Since heatis applied by conduction to thetop of the As soon. as the vacuumconnection 2| vacuum and the port 23.

V the closing of the exhaust valve, the closed end creases downwardly ofthe pellet,'-which is further aided by the chilling of the lower portionof the pellet.- The lower portion of the pellet remains permanently setor solid, while the upper portion increases in plasticity toward thetop, and has a maximum plasticity at the top which is in"thermal'contactwith the tubular vacuum connection 2|. When the upper portion of thepellet is moved inwardly and downwardly to close the bore l1 and formthe bridge H, the closed end. or

bridge Il -is brought into close relationto the chilled lower portion ofthe pellet l1, and this tends to further chill the bridge l1 so that itis rendered solid throughout the major portion of its verticaldimension, extendingiromits bottom I to substantially its upper face,while the upper face which contacts with the connection 2| remainspiasticized. ,"Ihe bore of the tubular pellet is therefore closed at thetop but remains open at the bottom. Since the same degree of vacuumisnow placed upon opposite sides of the closed end The numeral 23designates the glass tube or envelope of-a fluorescent lamp, having aglass base 33. Secured to the base 33 are contacts 3|, carrying mountwires 32. Thisglass base is provided centrally thereof with an exteriorrecess 33, having an opening 34 in its bottom.

or bridge l1 of the pellet, there is no tendency for such closed end tobe drawn down into the shell by the vacuum therein.

has moved downwardly and. closed the upper end of the tubular pellet byforming the bridge I1, the

The numeral 33 designates the bodyl rtion of a tubular vacuumconnection,.having a pipe 33 connected in its side and which leads to avacuum p p.

pipe 33, to supply the vacuum, or cut the same oil. 'At its lower end,the-body portion 3315 provided with asleeve- 31, provided at its lowerend with a head 38, having a frustro-conical or upwardly tapered face33. A cylindrical. opening 43 is formed in the head 33 and receives aplunger 4|. This plunger is provided withan intermediate enlargedportion grooves, The plunger 4| extend through an opening 44 and isprovided with a connection 43, by means of which the plunger may beraised and lowered with relation to the body portion 35. The

plunger passes through a packless gland 48, as

vacuum connection 2| and shell l0 are chilled by blowing cold air uponthe same at the points B and A, respectively, andthe closed pellet "isset and this occurs While the vacuum is still turned on. After theclosed pellet has set, thevacuum valve is closed, subsequently to whichan upward lifting force is applied to the vacuum connection 2 I, and'while this is done, the vacuum connection is heated at about the pointB and this .heat passes by conduction to the top of the pellet I1, andthis produces a plastic or molten layer or film at the top of thepellet, while the remainder of the pellet remains set, and when thisoccurs the vacuum connection 2| separates from the pellet. We alsocontemplate the use of a slightly different method. As soon as thevacuum connection 2| has moved downwardly to close the upper end of thetubular pellet and form the bridge I1,

as explained, Figure 5, and while the upper end of the pellet is stillplastic, the vacuum connection 2| is raised and separated from thetubular pellet,

and simultaneously with the raising of the vacuum connection, the vacuumvalve is closed, cutting ofl communication between thesource ofSimultaneously with or bridge H of the tubular pellet is chilled andset-throughout its entire vertical dimension by the lack of heat in theshell and by an additional blast of cold air applied to the top of thepellet.

The pellet should be rendered completely solid or set simultaneouslywith the breaking. of the vacuum'in the connection 2| exteriorly of thepellet,

so that the vacuum within the shell will not draw particles of solderdown into the shell, where they'would cause harmful results. All of thesteps of the method remain identical with those hereinbefore described.

In Figure 7'1, isshown a receptacle such as a. tin

can 26', which has been vacuum sealed in accordance with our method.This tin can has a top 21 provided with a recess 28, corresponding tothe recess 13, and receiving the tubular pellet II which has beentreated in accordance'witheither method described in to 6 inclusive. I

Attention is now called to Figures 8 to 15 in-I elusive.

connection with Figures l and the vacuum valve is closed and the vacuumshown. When the plunger 4| is in the lowermost position, it enters theopening 43 and closes the same and the lower end of'the plunger is thensubstantially flush with the-face 33, the plunger and face thenproducing a continuous surface.

lar, pellet having an upper tapered end 50 which was previously formedthereon. Downward pres.-

sure is'applied to the tool 48, while the glass base I 33 is heated, andthis heat passes by conduction to the tubular pellet, heating andplasticizing the outer surface or periphery of the tubular pellet andfusingthe same tothe wall of the recess 33 and the base of the same toform a vacuum tight joint between these parts. Before the upper end ofthe tubular pellet 41 has fused to the cold tool 48, this cold tool ismoved'upwardly and separated from the pellet. Instead of using thecoldtube 48, as described, the tubular vacuum connection, Figure 10, may beused.- If this is done, the sleeve 31 would be cold and brought downinto engagement with the upper tapered end 50 of the tubular pellet, 4 1and exert a downward pressure upon the same, while the base was heated.This action will fuse the pellet to the walls of the recess 33. ,Afterthe pellet is thus arranged within the recess 33 by the use of the coldtool 48 and fused 'to the wall of the recess 33, the face 33 of thesleeve 31 is brought into contact or engagement with the end so of thepellet,and the base so is 1 chilled, by blowing cold air upon the samewhile the sleeve 31 is heated and the plunger 4| is in the lowermostposition to cover the opening 43 also cut off by the plunger I. Thisheat passes by conduction through the sleeve 31 to the upper end of thetubular pellet, which has previously set, and the upper 'end of thetubular pellet is plasticizedand is fused to the face 33- of the sleeve31, Figure 10. The sleeve 31 and base 3|) are now.

A suitable valve (not shown) is con-' nected to the pipe 36 for openingand closing the- 42, having longitudinal oi. the

claims. 7

Having thus described the invention, what is 7 chilled by blowing coldair upon the same so that the pellet 41 and its end which is fused tothe face 88 are set, and the vacuum valve is now opened and the plunger4! is raised to uncover the opening 40, Figure 11, whereby the envelope28 is placed in communication with the source of vacuum'and properlyevacuated. While the I vacuum connection towardthe receptacle to aidpellet and the vacuum connection while said vacuum valve remainsopen,.the' plunger ll is' moved downwardly to enter and cover theopeningAl and the sleeve 31 is heated while the base 30 is chilled. The heatpasses by conduction through the sleeve I! to the upper end of thetubular pellet which plasticizes this upper end,

and when this occurs, the sleeve 31 and plunger ll are moved downwardlyand press the plasticized upper end of the tubular pellet downwardly andinwardly closing the upper end of the bore oi the tubular pellet byforming a bridge 41, the

in closing the tubular pellet, causingthe closed tu'bular pellet to set,applying atone. to the vacuum connection in a direction from thereceptacle, and again heating the outer end ofthe pellet to produce aplasticized layer betweenthe force is applied to the vacuum connectiom2. The method of vacuum sealing a receptacle having a metallic part,comprising bringing a tubular solder material pellet into contact withthe metallic part and placing the bore of the tubular pellet incommunication with the interiorof the receptacle, heating the contactingportions of the metallic part and pellet to cause them to fuse togetherand causing the same to subsequently cool, bringing a metallic tubularvacuum connection into contact with "the tubular pellet lower end of theplunger 4i and the face 38 forming: a continuous surface for thispurpose. The

lower end of the tubular pellet remains set due to its contact with thecold wall oi-the recess 33 and the lower end of the bore ll! of thetubular pellet remains open. The vacuum valve remains open during thisoperation. This operation is shown in Figure 12.

Withthe sleeve 31 in the lowered position and tubular pellet closed, asdescribed, the sleeve 31 is chilled and the base is chilled and thepellet is set, while the vacuum valve remains open,

the plunger II in the lowered position and the 13. The vacuum valve isnow closed while the plunger ll remains in the lowered position with thesleeve 31', and a lifting force is applied to the sleeve 31, Figure 14,and sleeve 31 is now heated, .while heat passes by conduction to theupper closed end of the tubular pellet, providing pellet, and when thisoccurs the sleeve 31 rises and separates from the tubular pellet. Whenthe sleeve 31 is thus separated from the tubularand placing the sameinto communication with the bore of the tubular pellet, heating the.con-

tacting portions of the tubular vacuum connection and the pellet tocausethemto iuse together and then allowing such partsto cool,evacuating the receptacle through the connected tubular vacuumconnection and tubularpellet, heating the tubular pellet to plasticizethe same, moving the tubular vacuum connection toward the receptacle toclose the'tubular pellet, and separating the vacuumconne'ction from theclosed pellet. 3. The method of comprising bringing the end of a tubularsolder material pellet into contact ,with'the metallic part and placingthe more of they tubular pellet in communication withthe opening,heating; the

a plastic or molten him at the top of the closed.

pellet a recess II is formed above the closed pellet ing wax 52, asshown'in Figure 15.

Attention is called to the fact that the solder material I! and thesealing was 41 are both formed of thermoplastic material. The thermoandthis recess is filled flush with a layer oi sealplastic material ofwhich the pellet is made, must have a lowermelting point than theenvelope to which it is attached, and a higher melting point than thetemperature at which the device operates or is used in its finalapplication.

It is to be understood that the forms of our invention herewith shownand described are to be taken as preferred examples of the same, andthat various changes in the shape, size, and ar- I rangement of partsmay be resorted to, and that.

changes may be made in the order of the steps of the method, withoutdeparting from the spirit invention or the scope ot the subioinedclaimed is:

l. The method of vacuum sealing-a receptacle having an opening,comprising attaching a tubular thermoplastic pellet .to the receptaclefor rel-mm: a vacuumtight ioint and .placing the bore 01- the pelletin"communication with the nected tubular connection and tubular pellet,

contacting portions of the metallic part and e'pellet to cause them tofuse together, then causing the contacting-portions to cool, bringingthe end of a metallic tubular vacuum connection into contact with theouter opposite end of the tubular pellet, heating, the contactingportions 01' the tubular connection and pellet to cause them to fusetogether, then allowing such parts to cool,

evacuating the shell through the connected tubular connection andtubular pellet, again heating the outer endof the tubular pellet toplasticize the same, moving the tubular connection toward the shell toapply pressure to the plasticised outer end of the tubular pellet toclose the same,

moving the tubular connection from the tubular pellet whilesimultaneously cooling the outer closed end of the pellet. 1

4. The method of vacuum sealing a shell having a metallic part,comprising bringing the end of a tubular solder material pellet intocontact with the metallic Part and placing the bore. of the tubularpellet into communication with the interior of the shell, heating, thecontacting por-. tions and pellet to fuse them together, then causingthe contacting portions to cool, bringing the end of a metallic tubularvacuum connection into contact with the outer opposite end or thetubular pellet, heating the contacting portions of the tubularconnection and pellet tome them together, then allowing such contactingportions to cool, evacuating the shell through the conagain, heating theouter end of the tubular pellet to plasticize the same whilecooling the.inner end of the tubular pellet to prevent the same being plasticized,moving the tubular connection toward the shell to aid in closing thebore of the tubular pellet by the plasticised solder, moving the tubularconnection-from the tubular pellet vacuum"sealingv ashell having ametallic part provided with an opening,

I cooling the outer end of the pellet so that it sets.

5. The method of vacuum sealing a shell having a metallic part providedwith a recess having an apertured head, comprising inserting a tubularsolder material pellet into the recess so that its inner end contactswith the head, applying pressure 'to the outer'en'd of the tubularpellet to cold form its inner end to correspond to the shape of saidhead and cold form its outer end into a selected shape, applying heat tothe contacting inner end of the pellet and the head to cause theseportions to fuse together, then causing these portions to cool, causingthe outer formed end of the tubular pellet to enter a correspondinglyshaped recess in a tubular vacuum connection; heating the outer formedend of the tubular pellet so that it becomes fused to the wall of therecess, causing these parts to cool, then evacuating the shell throughthetubular connection and tubularpellet, again applying heat to theouter end 01' the tubular pellet to' plasticlze the same, then movingthe tubular connection axially toward the tubular pellet to aid inclosing its bore, then moving the tubular connection axially from thetubular pellet to separate the same therefrom while simultaneouslystopping the evacuation of the shell through the tubular connection andtubular pellet and simultaneously cooling the outer end of the pellet sothat it sets. a

6. The method of vacuum sealing a shell having a metallic part providedwith a recess having an apertured head, comprising inserting a tubularsolder material pellet into the recess so that its inner end contactswith the head, applying heat to the shell adjacent to the recess so thatthe inner end of the pellet is heated by conduc- 10 a ticized portion toclose the bore of the tubular pellet, and separating the vacuumconnection from the closed pellet while the tubular pellet remainsattachedto the receptacle;

8. The method of vacuum sealing a receptacle,

comprising arranging a tubular thermoplastic pel1et with its boreincommunication with the" interior of the receptaclaefiecting a fused vacuum tight joint between the pellet and the wall of the receptacle,bringing a tapered end wall of a tubular vacuum connection into contactwith the outer free end wall of the tubular pellet and effecting a fusedvacuum tight joint between such 7 end walls, evacuating the receptaclethroughthe connected vacuum connection and tubular pellet, heating theouter portion of the tubular pellet to plasticize the same, mo'ving'thetubular vacuum connection toward the receptacle to cause the tapered endwall of the tubular. vacuum connec-' tion to crowd the plasticizedmaterial inwardly andclose the bore of the tubular pellet, and sepa-Vpellet in communication with the interior of the receptacle, fusing atubular vacuum connection tion and fused to the head, then causingtheseparts to cool, then evacuating the shell through the tubularconnection and tubular pellet, again applying heat to the tubularconnection adjacent to the pellet to cause the outer endof the pellet tobe heated and plasticized, then movingthe tubular connection axiallytoward the tubular pellet to aid in closing its bore, then moving thetubular connection axially from the tubular pellet to separate the sametherefrom while simultaneously stopping the evacuationof the shellthrough the tubular connection and tubular pellet and simultaneouslycooling the outer end of the pellet so that it sets;

7. The method of vacuum sealing a receptacle j .having a recessaccessible from the exterior, said recess having a bottom provided withan open ing, comprising arranging a tubular thermoplastic pellet withinthe recess, effecting a fused vacuum tight joint between the pellet andthe wall of the'recess. bringing the end wall of a tubular vacuumconnection into contact with the outer free end wall of the tubularpellet and effecting a fused vacuum tight joint between such end wa lsevacuating the receptacle through the connected vacuum connection andtubular pellet,

with the outer end of the tubular pelle for forming a vacuum-tightjoint, evacuating he receptacle through the tubular connection andtubular pellet, applying heat to the tubular connection andthereby-causing the tubular connection to heat the outer end of thetubular pellet by conduction and plasticize such outenend, moving thetubular. connection toward the receptacle to'close the tubular pellet,causing the closed end of the pellet to set, breaking the vacuum withinthe tubular connection, and separating the tubular connection from thetubular pellet.

v 10. The method of vacuum sealing a receptacle, comprising effecting a,fused vacuum-tight joint between a tubular thermo-plasti'c pellet andthe "receptacle and placing the bore of the tubular pellet incommunication with the interior oi the receptacle, eflecting a fusedvacuum-tight joint between a tubular vacuumconnection and the free end01' the tubular pellet, evacuating the receptacie through the connectedvacuum connection and tubular pellet, heating the tubular.

pellet to plasticize a portion of the'same, moving the vacuum connectioninwardly toward the re ceptacle to' aid in closing the tubular pellet,and separating the vacuumconnection from the. closed pellet at a pointadjacent to the free endof the tubular vacuum connection whilethe'tubular.

between the end of'a tubular vacuum connection 7 and the free end ofthetubular pellet, evacuating V the receptacle through the connectedvacuum connection and tubular pellet, heating the outer end of thetubular pellet to plasticize the same,

heating the tubularpellet to plasticizea portion ward the receptacle andthereby causing the plasof the same, moving the vacuum connection .to-.

moving the vacuum connection inwardly toward the receptacle to closethe. bore of the tubular pellet by the plasticized outer portion,andfseparating the vacuum connection, from the outer closed end of thepellet.

12. The method of vacuumsealing a receptacle,

r a n g comprising fusing to the receptacle for forming a vacuum tightjoint 2. tube having a lower fusing point than the receptacle andplacing the bore of the tube in communication with the interior of thereceptacle through the connected tube and tubular connection, heatingthe outer end of the tube to plasticize the same,'moving the tubularvacuum connection toward the receptacle for aid- .ing in closing thetube, and separating the tubular vacuum connection from the tube at apoint ad- Jacent to the free end of the tubular vacuum connection whilethe tube remains attached to the receptacle.

aeeaese same, moving the tubular vacuum connection toward the receptaclefor aiding in closing thetube and shortening the tube, and separatingthetubu-. lar vacuum connection from the tube while the tube remainsattached to the receptacle.

14. The method of vacuum sealing a receptacle, comprising placing 'atube having a lower fusing point than the receptacle into contact withthe receptacle heating the receptacle and thereby heating the tube byconduction and fusing the same to the receptacle for forming a vacuumtight Joint and placing the bore of thetube in communication with theinterior of the receptacle,

13. The method of vacuum sealing a receptacle.

comprising fusing atube having a lower fusing point than the receptacleto the receptacle for forming a vacuum tight joint and placing the boreof the tube in communication with the interior of the receptacle, fusingthe free end of placing the free end of a tubular vacuum connectionhaving a higher fusing point than the tube in contact with thelouterfree end of the tube, heating the tubular vacuum connection and causingthe same to heat the outer end of the tube by conduction and therebyfusing the tube to the tubular vacuum connection and placing the bore ofthe tube in communication with the.bore of the tubular, vacuumconnection, evacuating the receptacle through the connected tube andtubular connection, again heating the tubular vacuum connection to causethe same to heat the tube by conduction and plasticize the same, movingthe tube to the end of a tubular vacuum connection having a higherfusing point than the tube for forming a vacuum tight joint and placingthe bore of the tube in communication with the bore of the tubularvacuum connection, evacuating the receptacle through the connected tubeand tubular connection, heating the tube to plasticize the ceptacle foraiding in closing the tube, and separating the tubular vacuum connectionfrom the the tubular vacuum connection toward the reouter free end ofthe tube while the tube remains attached to the receptacle.

a CARL HERZOG.

PAUL A. nation.

